The present invention relates to angioplasty. In particular, the present invention relates to an innerless dilatation balloon catheter.
Angioplasty has gained wide acceptance in recent years as an efficient and effective method for treating vascular diseases. In particular, angioplasty is widely used for opening stenoses in coronary arteries. It is also used for treatment of stenoses in other parts of the vascular system.
A common form of angioplasty makes use of a dilatation catheter which has an inflatable balloon at its distal end. With the aid of fluoroscopy, a physician guides the catheter through the vascular system until the balloon is positioned across the stenosis. The balloon is then inflated by applying fluid pressure through an inflation lumen to the balloon. Inflation of the balloon causes stretching of the artery and pressing of the stenosis-causing lesion into the artery wall to reestablish acceptable blood flow through the artery.
Dilatation catheters can generally be divided into those which are fed over a guide wire (i.e., "over-the-wire" catheters) and those catheters which serve as their own guide wire (i.e., "fixed-wire" catheters). Both types of catheters have advantages and disadvantages.
Innerless dilatation balloon catheters have been developed in an attempt to obtain some of the advantages of a fixed-wire catheter while still retaining the advantages of an over-the-wire catheter. These innerless catheters feature a shaft having a single lumen which acts as both an inflation lumen and a guide wire lumen. A lumen extension extends through the balloon, which is mounted on the distal end of the shaft. The shaft lumen is in fluid communication with the interior of the balloon. The guide wire extends through the shaft lumen, he lumen extension and out the distal end of the balloon.
Examples of innerless dilatation balloon catheters are shown in U.S. Pat. Nos. 5,032,113 and 5,035,705 by Matthew M. Burns
One consideration in the successful design of any innerless dilatation catheter is that during balloon inflation the inflation fluid must be permitted to flow from the shaft lumen to the interior of the balloon, without substantial leakage of inflation fluid through the lumen extension and out the distal end of the catheter. Similarly, during balloon deflation, blood must not be drawn into the catheter through the lumen extension to such an extent that the balloon will not deflate.